1. Field of the Invention
This invention relates to the chemical arts. In particular, it relates to compositions useful as polishes for refinishing scratched surfaces.
2. Discussion of the Related Art
Compact disks have become increasingly popular in a wide variety of applications, because of their ability to digitally record large amounts of information. As shown in the figures, a typical compact disk contains three layers. The top layer 10 is a protective layer generally formed from an acrylic plastic film. The middle layer 12 is a reflective layer generally formed from aluminum or silver.
The bottom layer 14 is a substrate containing an optical surface. The optical surface has the digital information recorded on it in the form of a spiral track having sequences of minute pits. An optical read-out system is used to decode the information contained on the spiral track. If a laser beam passes through the bottom layer and over the surface of the track, the beam is reflected, caused to pass back through the bottom layer, and then caused to contact a photodiode, so that an electric signal is produced. In contrast, if the beam encounters a pit in the track's surface, it is not reflected and no signal is produced.
The bottom layer is made of a plastic material. Polycarbonate is the preferred plastic, because it is very strong and optically pure. A significant drawback to polycarbonate, however, is that the exterior surface of the polycarbonate layer is prone to scratching. If the exterior surface becomes too scratched, it can interfere with the passage of the laser beam through the substrate. When this happens, the optical read-out system will backtrack until it reads an unaffected sequence of pits and then continue. Often this leads to a "skip" or a constant "skipping", as the player gets stuck on one sequence and the compact disk stops playing.
Accordingly, there exists a definite need for a simple and effective method to remove scratches from and refinish the surface of a compact disk to prevent skipping. There has existed a further need for a polishing composition which can be applied to the surface of a compact disk to remove scratches and restore its optical quality. The present invention satisfies these and other needs and provides further related advantages.